Metal coated ferrous article and process of making it



F. M. cRAPo 1,984,335

METAL `COATED FEROUS ARTICLE AND PROCESS OF MAKING IT Filed Aug` 12 mmh l SE Patented Dec. l1, 1934.

c UNITED STATES PATENT OFFICE METAL COATED FERROUS ARTICLE AND PROCESS OF'MAKING IT Frederick M. Crapo, Muncie, Ind., assignor to Indiana Steel la Wire'Company, Muncie, Ind.

` a corporation of Indiana Application August 12, 1931, Serial No. 556,631

8 Claims.

coating whose outer part is of very pure metal,l

while the inner part is rmly associated with the ferrous base by inter-alloying.

I n carrying out my invention, I apply the coating in two parts. The iirst part is a zinc coating, applied by the hot-galvanizing process,

wherein there is a certain. inter-alloying bef tween the zinc and the ferrous base. The second part is also a ,zinc coating, but is deposited over the first zinc coating otherwise than by hot-galvanizing, desirably by electro-deposition;

whereby this second part of the coating may be made comparatively pure and free from alloy, and also comparatively heavy, and yet will be firmly joined to the article byV its adhesion to Athe surface produced by the hot-galvanizing. As

a result, I am able to get' a heavy coating of zinc, of which the inner part is alloyed with the ferrous base while the outer part is of comparatively -pure zinc.

In carrying out my invention, whether on ferrous wire or on other ferrous articles, the

coating processes may be either continuous'or by batches; but I prefer the continuous process, especially for wire. The accompanying drawing illustrates my invention. In such drawing, Fig. 1 is. an enlarged perspective view pf a wire coated in accordance with my invention, with the coatings much magnied in thickness, and without any attempt'to `indicate any inter-alloying; andFig. 2 is a` diagram showing a continuous processfor coating ferrous wire in accordance with my invention. o 1

I will describe my invention in connection with the continuousA process indicated in Fig. 2, although it is not limited to a continuous proess. The wire to be coated may be a ferrous wire of any character, prepared for coating in any (Cl. ill-68.2)

zinc adheres to and alloys with thersurface of the wire to provide the usual hot-galvanizing. If desired, although it is not necessary, the zinccoated AWire after it emerges from the bath l5` of molten zincmay pass through a wipe i6.- Also, although it is not essential to my inven tion, the zinc-coated wire may `nowreceive a heat treatment if desired,- asv by being passed I through a heat-treating furnace 30.

Up to this point, the wire produced is hotgalvanized wire, and may be ofany type. The

hot-galvanized coating thereon forms the iirst part ofthe coating of my present invention.

'Ihe hotfgalvanized wire is now treated to ap- 'ply the second part of my coating thereto. This treatment may bemade immediately after the wire has been hot-galvanized, in thesame continuousprocess; or it may be applied at some later time, although I deem that less desirable.-

In the arrangement shown in Fig. 2, the second half ofthe coating is applied inthe same continuous process. The `hot-galvanized wire 10, after leavingl the bath l5 of molten zinc, and the wipe 16 and/or heat-treating furnace 30 if they are used, is desirably passed through a cleaning bath 17, 'of any suitable character, to prepare the wire for the subsequent coating. The wire 10 then passes to the second coating apparatus, for .which I prefer an electro-plating bath 18. In this'bath the moving wire is the cathode, being connected to the negative side of a. suitable electric supply-circuit 19, as by trolleys 20. The plating bath also has a suitable anode 21 connected to the positive side of the supply-circuit. I have indicated this electro-plating bath, as well as the other baths shown, merely diagrammatically; as they may take any suitable form. From the' electro-plating bath, the now `double-coated wire may pass, through an intervening washing bath 22 and over or through a drier 23 if desired, to a takeup reel 24; by which take-up reel the power is applied for moving the wire.

The electro-plating bath 18 contains an electrolyte suitable for: plating zinc on to the already hotfgalvanized wire: and the anode 21 is of suitable material for zinc plating. In consequence, the second part of the coating, as well as the rst or hot-galvanizing part, is a zinc coating. That is highly desirable to get a heavy zinc coating, and one that has its outer part of substantially pure zinc.-

The nature of the electrolyte in the 1electro-` plating bath ,18 may vary in, accordancewith known processes for zinc plating; and so may u a galvanized coating 26 of zinc is'applied by any available hot-dip process of galvanizing;

Iand over the coating 26 is an outer zinc coating 27 which is applied by a coating process other than hot-g'alvanizing, and desirably by electro-deposition. The coating 26 alloys with the ferrous base 25 in the hot-galvanizing process, in a manner which is impossible to show in the drawing,l but which is well-known.

It has heretofore been proposed to coat a ferrous article by two successively applied zinc coatings, the first by electro-deposition and the second by hot-galvanizing. See for instance- .Patent No. 1,552,040, granted to Frank F. Fowle and myself on September 1, 1925. With the successive coatings applied in that order, however, the same result is not obtained which I obtain by-my present process; in which the first coating is by hotga1vanizingand in which ,y a certain alloying action takes place between the zinc and the iron during the I claim as my invention:

1. A zinc-coated ferrous article, comprising a ferrous base having a hot-galvanized coating of zinc thereon, and over that'a. second coating of zinc applied by a different process and comparatively pure and free from alloy and comparatively heavy.

hot-galvanizing.

2. A @zinc-coated ferrous article, comprising a ferrous base having a hot-galvanized coating of zinc thereon, and over that an electro-deposited coating substantiallywholly of zinc.

3. A zinc-coated ferrous wire, comprising a ferrous base-wire having 'a hot-galvanized coating of zinc thereon, and over that a second coating of zinc applied by a different process and comparatively pure and free from alloy and comparatively heavy.

4. A zinc-coated ferrous wire, comprising a ferrous base-Wire having a hot-galvanized coating of zinc thereon, and over that an electrodeposited coating substantially wholly of zinc. 5. The process of zinc-coating a ferrous article, which consists in applying to it a zinc coating by the hot-galvanizing process, and applying to the hot-galvanized ferrous article by a process other than lhot--galvanizing a zinc coating which is substantially pure` and free from alloy and comparatively heavy.

6.- The process of zinc-coating a ferrous-article, which consists in applying to it a zinc coating by the hot-galvanizing process, and applying to the yhot-galvanized ferrous article 'by substantially wholly electro-deposition a coating of zinc. Y

7. The process of zinc-coating a wire, which consists in passing it successively through a bath ofmo1ten zinc and through an electro-plating bath' containing a suitable electrolyte for' de-` positing a coating substantially wholly of zinc.

8. The process of zinc-coating a Wire which consists of subjecting it to two dissimilar zinccoating processes, of which the first is zinccoating by hot-galvanizing and the second de posits a zinc coating which is comparatively pure and free from alloy and comparatively heavy.

'FREDERICK M. caAio. 

